Online social media services, such as social networking sites, search engines, news aggregators, blogs, and the like provide a rich environment for users to comment on events of interest and communicate with other users. Social media content items authored by users of social networking systems often include references to media events that appear in time-based media such as television shows, news reports, sporting events, movies, concert performances, and the like. However, although the content items can sometimes refer to specific media events that appear in the time-based media, the social media content items themselves typically are isolated from the media events and time-based media referenced by those content items.